The above graph compares the rate of goals plus assists each season of the the two players considered the greatest of the modern era, Lionel Messi and Cristiano Ronaldo.

Lionel Messi's performance in his early years were much stronger than Ronaldo's which reflect his greater natural ability. In his first season he had nearly double the rate of goal plus assists of Ronaldo's first season. Although Ronaldo has become comparable to Messi in goals scored after he moved to Real Madrid often surpassing Messi in this area, Messi continued to have more assists which is why he tends to be higher in the graph in most seasons. In recent seasons, Ronaldo's drop in overall attacking performance is more consistent. Messi actually had one of his best seasons in 2018/2019 in which he had a higher rate than Ronaldo's best season and it was followed by another very strong season. Ronaldo dropped to below 1 in 2018/2019 (rounded on the graph to 1) and has remained so for the next 3 seasons. It is clear that he has declined due to age.

Messi's recent season at PSG wasn't his greatest season but it's worth noting that he played as a winger which probably explains why his stat dropped below 1 for the first time in well over a decade although his final season at Barcelona suggests that it may be part of a general decline as well although the evidence is less conclusive than in the case of Ronaldo and we will have to see how Messi performs in the next season to determine for sure.